#define _CRT_SECURE_NO_WARNINGS 1
#include"stdio.h"
int main()
{
	int arr[10] = { 0 };
	int sum = 0;
	for (int i = 0; i <= 9; i++)
	{
		scanf("%d", &arr[i]);
		sum += arr[i];
	}


	float se = sizeof(arr) / sizeof(arr[0]);
	printf("%f\n", sum/se);
	return 0;
}